Mitochondrial glutathione peroxidase 4 is indispensable for photoreceptor development and survival in mice.

Kunihiro Azuma, Tomoko Koumura, Ryo Iwamoto, Masaki Matsuoka, Ryo Terauchi, Shu Yasuda, Tomoyasu Shiraya, Sumiko Watanabe, Makoto Aihara, Hirotaka Imai, Takashi Ueta

The Journal of biological chemistry 2022 Apr

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Glutathione peroxidase 4 (GPx4) is known for its unique function in the direct detoxification of lipid peroxides in the cell membrane and as a key regulator of ferroptosis, a form of lipid peroxidation-induced nonapoptotic cell death. However, the cytosolic isoform of GPx4 is considered to play a major role in inhibiting ferroptosis in somatic cells, whereas the roles of the mitochondrial isoform of GPx4 (mGPx4) in cell survival are not yet clear. In the present study, we found that mGPx4 KO mice exhibit a cone-rod dystrophy-like phenotype in which loss of cone photoreceptors precedes loss of rod photoreceptors. Specifically, in mGPx4 KO mice, cone photoreceptors disappeared prior to their maturation, whereas rod photoreceptors persisted through maturation but gradually degenerated afterward. Mechanistically, we demonstrated that vitamin E supplementation significantly ameliorated photoreceptor loss in these mice. Furthermore, LC-MS showed a significant increase in peroxidized phosphatidylethanolamine esterified with docosahexaenoic acid in the retina of mGPx4 KO mice. We also observed shrunken and uniformly condensed nuclei as well as caspase-3 activation in mGPx4 KO photoreceptors, suggesting that apoptosis was prevalent. Taken together, our findings indicate that mGPx4 is essential for the maturation of cone photoreceptors but not for the maturation of rod photoreceptors, although it is still critical for the survival of rod photoreceptors after maturation. In conclusion, we reveal novel functions of mGPx4 in supporting development and survival of photoreceptors in vivo. Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.

Citation

Kunihiro Azuma, Tomoko Koumura, Ryo Iwamoto, Masaki Matsuoka, Ryo Terauchi, Shu Yasuda, Tomoyasu Shiraya, Sumiko Watanabe, Makoto Aihara, Hirotaka Imai, Takashi Ueta. Mitochondrial glutathione peroxidase 4 is indispensable for photoreceptor development and survival in mice. The Journal of biological chemistry. 2022 Apr;298(4):101824